The FBI and the U.S. Justice Department are joining the investigation into a hoax that sent SWAT teams to a Long Island home, after a call about an armed man barricaded with possible victims inside.

At one point, every police officer on duty in the city of Long Beach was on the scene, along with heavily armed Nassau County SWAT teams and hostage negotiators.

It ended nearly two hours later, only after a teenager took off his headphones and got up from his computer screen, and realized his home was surrounded.

He told detectives he had been playing the computer game known as "Call of Duty." Police now theorize that one of the boy's anonymous, online opponents called in the hoax to the city's police department.

"A young male called in and stated that he just killed his mother and his brother, gave his address, and said he was going to kill the first responders when they arrived," said Long Beach Police Commissioner Michael Tangney.

It's become known as 'Swatting', when the loser of a computer game calls in a hoax to harass his opponent. A similar stunt in New Jersey last year led to the arrest of a teenager in Florida.

"Once we catch this person, then that will let others know that this will not be tolerated," said Tangney.

Officials insist that an arrest is only a matter of time.

"We have them identified by screen names and things of that nature. To get their actual names is going to take a little bit of time," said Tangney. ('But you intend to do that?') "Absolutely," he said.

"When they're playing video games, if they lose during the game they try to get information on their opponents," said Tangney. "If they do get the information, they call the police and identify themselves as that person and say that they killed somebody so that the police get this response."

The police response cost tens of thousands of dollars, and two Nassau County police officers suffered minor injuries in a traffic accident responding to the call.

Nassau County District Attorney Kathleen Rice issued a statement on Tuesday's "swatting" incident, calling it an "outrageous waste of law enforcement resources and taxpayer dollars."

"Through a collaboration with our law enforcement partners, we will use every tool we have to track down whoever threatens public safety like this," it said. "'Swatting' is a serious crime that endangers first responders and those in legitimate need of their help. We will hold any perpetrators accountable and seek restitution for the tax dollars wasted."